Today's confirmation that Apple is going x86 makes today a historic day in the industry. It may mean that Microsoft might see a few percent decline of their market share the next few years, but what about Linux? If Linux were to lose an equal amount of share it would alter its spread to the desktop, a spread that has been very positive so far.

"The percentage of Mac users using a Linux on PPC is way lower than the percentage of x86 users also using Linux. For example, 3% of all x86 users use Linux according to some recent stats, but less than 1% of the 3% of the Mac users use Linux (that's 0.33%)."

Your logic is flawed. Apple was expensive, so to buy Apple in the sole pourpose to run linux was pretty ridiculous. Most of Apple users is not that computer savvy (the whole goal of Aple was to make OS easy). OS X is mostly for people who love Apple.
Again Intel or not, it will be proprietary hardware more expensive that white box so buying iMac (Intel-Mac) to run linux will make even less sense.
OS X on Intel will have exactly the same problems as on PowerPC: quite limited choice of the hardware, and slower that other OSes. So even it will be relatively faster that on PPC it will be still behind.
Most of the linuxers represent young generation, pretty much discovering/learning OS internals, people who like "tinkering". For them linux cheaper and much more flexible is OS of choice.
In other words, The balance will stay for very long time.

"Quoting myself:"
You should not qoute yourself, I remember you bashing whiners who asked about iMac five years ago.
Also articularly if it is about MS because it was so obvious.
Redmond will support Apple as before because of the same reasons:
they need "competinion".
Linux will be only in danger when MS stops to support Apple: this would mean that Apple is a menace for MS. So even more for linux.
In other words this was so predictable that "quoting yourself" is rather funny.

"For example, OSX just "works with the hardware" rather than "Gnome/KDE working on TOP of a kernel". "
That is because hardware for Apple is so limited, You can do that with linux too if buying hardware for linux. I never had compatibility problems because I knew what I need. Usually people are getting box with windows then eventually they try linux on the hardware that may not work.

"With Mac OS X's great desktop experience, why would anyone use X11 and its DEs?"
This one is as subjective as possible.
I prefer Pisarro over Signac, so even Signac may be the best visual experience for you and that only means we prefer different estetics.

I don't know if OS X will take over linux fans. I don't care what other people are using.
Ther whole point is, that your argumentation is rather weak.